United We Stand
by littlebearcub
Summary: After Clary is partnered with the egotistical boy who's gone out of his way to aggravate her for years, she'll have to put her hatred to rest in order to have any chance at bringing down a mass terrorist organization. Yet as they are sucked deeper into the ruthless plot, it becomes apparent that something stronger than hatred is at work, and it may make or break their relationship.
1. Not The Plan

**A/N: Hello my lovelies! I've been playing around with this idea for a while and I think I've got it sorted, henceforth I bring to you my latest fic! (For anyone who reads Wishing On Stars, I promise you I haven't abandoned it!) Now, I've never written anything about terrorism or secret government agents, so I think this'll be a nice and fun change from what I've done before. Some characters might be a little OOC but I think it's fun to spice things up. :)**

**If I owned The Mortal Instruments I wouldn't be writing this. **

* * *

"Nice, Fray!"

Clary wiped away the blood from her mouth and extended the other to the brown haired boy she'd been fighting. "You're not so bad yourself, Lewis. Just react quicker. An enemy would have shredded you by now."

He fixed his askew glasses and offered her a lopsided grin. "You know that I'm more tech-savvy. Combat isn't my forte." he pointed out sheepishly.

"I thought you might have picked up _something_ from playing Halo!" she exclaimed, earning her a laugh from her best friend. Clary and Simon had been best friends since he came to the American Intelligence Agency - or AIA - aged six. They'd trained together in hopes of becoming agents, and lo by hold they'd reached that goal ten years later. They were clearly ideal partners, though the decision wasn't theirs to make. That rested in the hands of their superiors.

As Clary bent down to retrieve her water bottle from where she'd left it on the bench, Simon let out a soft wince. "You've bruised my ribs."

She gulped down some of the ice cold liquid and laughed. "You'll live," she assured him mockingly, throwing the bottle over to him as she wiped beads of sweat from her forehead. "I'm going to get changed. I feel like I'm going to drop dead on my feet and I'd rather not be covered head to toe in sweat if it comes to that."

"When we become partners, I _won't_ be the one to pick up your sweltering body," Simon teased. "You can count on that."

She laughed as she headed out to the changing room, taking her bag and slipping out of her training clothes - this consisted of a white camisole, a black t-shirt that slipped off one shoulder and black leggings - as she turned on the shower. The water was at that perfect temperature between cold and hot which was a relief to Clary; she preferred her water neutral.

After a quick rinse, she dried herself off and changed into a plain dark green t-shirt and ripped denim jeans, stuffing her other clothes into her bag. She also took her carroty curls down from the ponytail it was in so it brushed comfortingly against her shoulder blades. _Much better._

Simon was waiting for her outside, having changed into a geeky shirt, baggy trousers and tatty greying trainers. "Shall we go to the canteen? I could _really_ do with a sugar injection."

"In other words, you just want to see Isabelle because you know she'll be down there." Clary rolled her eyes and snickered. Simon undoubtedly had a crush on the beautiful yet deadly Isabelle Lightwood. She seemed like a ditzy and flirtatious girl on first encounter, but once you got to know her she was almost terrifying. Once she'd actually put a knife to Clary's throat and threatened to slit it all because she'd hidden her mascara. They'd moved on since then and got along okay, though it was amusing to watch Simon moon over her.

Her best friend looked incredulous. "Now, I never said anything when you went through your Jace phase, so-"

Clary cut him off with a wave of her hand. "That was a stupid little thing that happened eight years ago, Simon. You don't need to keep bringing it up."

He shrugged. "Let's just go eat before I die." he said, leading the way down the maze of corridors which Clary had memorized backwards as well as forwards. Probably the only perk of growing up there for fifteen years.

They were about to open the great double doors into the canteen when they heard a chime over the intercom. "_Good afternoon agents. Can Magnus Bane, Helen Blackthorn, Clarissa Fray, Jonathan Herondale, Jordan Kyle, Simon Lewis, Alexander Lightwood, Isabelle Lightwood, Aline Penhallow and Maia Roberts please report to the main office? Over and out._"

Simon and Clary shared a knowing look. This meant they'd finally been partnered up with their fellow classmates. Though of course, they'd put the two best friends together, right? It would be dumb not to.

Clary was only just able to contain her excitement about the matter as they made their way back down many corridors.

* * *

"Please take a seat, everyone. Thank you for being so punctual."

Clary had obviously taken the seat next to Simon, but what she hadn't calculated was that one seat was left next to her, and the only person who didn't have a chair yet was the one person she point blank despised.

Said person immediately slumped down next to her, a mischievous grin spreading across his face. "Hey, Shortie."

Clary turned her face away from him with a scowl, just as the man who summoned them sat in his chair. Lucian Graymark - though he preferred Luke - was their mentor and had been part of the important decision. He'd been like a father to them all, but to Clary he was the only father she'd known. She'd come under his care at the tender age of one after her mother was killed and her father just couldn't take her on for reasons classified. Nonetheless, Clary loved Luke in the way a daughter would love her father, and he had always taken care of her, even with the other trainees to worry about.

"Now, you all passed with flying colours as you know and have since been promoted to agents," Luke explained, folding his arms over his chest. "I have been in taking with Andrew Blackthorn and Robert Lightwood about partners which is part of why I have summoned you here today, but the main reason is the mission you'll all be on."

Clary's interest perked immediately as Luke produced a stash of folders across his desk. They had all been put on a mission already?

Luke opened one folder to reveal profiles of two men. "Valentine Morgenstern and Axel Mortmain. Leaders of the infamous Circle. I assume you've heard of The Circle?"

It was impossible_ not_ to have heard of them in the AIA. The Circle were a large criminal organization who were notorious for a number of things from robberies to manslaughter. For some time now word had got out that they were planning full-scale attacks, so they had to be stopped before they became unstoppable.

"You have been dispatched as a team to take out The Circle with whatever means necessary," Luke went on. "Yes, you'll be working as a team, but you'll mostly be with your partner which leads me onto who that will be for each of you."

Clary and Simon exchanged a gleeful look. _Everyone_ knew how close they were, so if they were partnered they'd be an effective team in all missions. They'd proved this to Luke many times; there was absolutely no reason for them not to be partners!

"You'll be working with this person indefinitely regardless if you like them or not. They'll be your constant companion and you'll be responsible for looking after each other. Confide in them with your theories and findings, keep them safe and simply just cooperate. Even if you hate the person, most partners end up becoming close friends once they get used to each other. If you're lucky you might be partnered with someone you're already very good friends with, but you can't always work with your friends."

_He can't have separated Simon and I... has he? _Clary was now internally panicking. If they were to be separated, who would Luke and the others have put her with?

"We have looked at your strengths and weaknesses in order to put you with a partner. Some of you are at totally different poles and some of you are similar." Luke fished out another piece of paper and coughed to clear his throat. "Alec, please stand."

The tall ink haired boy with piercing blue eyes stood up nervously, his gaze shifting from his hands to Luke and back down. Luke smiled at him. "Alec, you will be working with Helen," he announced, gesturing for the blonde girl to rise. "Both of you are strong mentally and good with forensics, plus you have worked well in previous exercises. Alec, your talent lies in shooting and Helen's in physical combat so if the worst comes to the worst we think you'll be okay."

The two smiled and Alec went over to sit with her, so Luke continued reading down his list. "Magnus, please stand."

Clary had been quite fond of the eccentric glitter-loving maniac who stood up. He'd always been nice to her, even if he was a little odd in comparison to everyone else. If Clary drew the group, Magnus would be the sharpest and most colourful.

"Magnus, you will be working with Maia. You're a fast thinker who can adapt in difficult environments and Maia's skilled in most forms of combat, plus both of you have keen eyes so you can detect when something's wrong in the surroundings."

The two were conveniently next to each other anyway so Magnus just grinned as they returned to their seats. "Hey partner."

"Simon, please stand." Luke ordered, raking a hand through his brown hair thoughtfully.

Giving Clary's hand a reassuring squeeze, Simon got up onto his feet and fixed an expectant gaze on Luke who's eyes scanned down the file he held. "Simon, you will be working with Isabelle."

Clary felt quite deflated as her best friend's partner rose up from her chair. She was absolutely _certain_ that she and Simon would end up together, but Isabelle was a nice girl. Even if she could break your bones with no mercy, she'd fiercely protect and look after the awkward yet brilliant nerd. But who had Clary been partnered with?

"Isabelle, you clearly have a taste for the combat and action, and Simon, you're obviously very comfortable with computers and complicated technology. You may be very different, but you might learn something from each other and we think your differences will unite you."

Isabelle shuffled over on the other side of Simon and offered him a smile which he returned bashfully, forcing a snort out of Clary.

The only people left were Aline, Jordan, Clary and the arrogant prick next to her.

"Jace, please stand."

With a smirk he stood up, holding himself up with more confidence than actually necessary.

"Jace, you will be working with Clary. Both of you are remarkable in combat, but Jace is clearly the better athlete and thinks out plans in greater depth. Clary, you can easily adapt in difficult circumstances and can react swiftly in fights or emergencies. We think you could perhaps teach each other to fill in the gaps where you slip up; once you conquer that you'll be a great team."

Clary couldn't believe her ears. She'd been partnered with the one person she didn't want to touch with a bargepole; the one who'd been responsible for making her life a living hell.

She'd been partnered with Jace Herondale; the egotistical bastard who she had once been friends with until eight years ago.

* * *

**Thoughts? I know that this was quite boring but things begin picking up and the many arguments between Jace and Clary kick off next chapter... the other team members will be developed gradually as the story goes on. ;)**


	2. Bittersweet Memories

**A/N: I've had a generally good reception from the first chapter so I'd like to thank you all! It did bring a smile to my face when I was notified of a new follower/favourite/review. :) So here is chapter two...**

**After reading over the last chapter I've just realised I've made a small mistake. Had a dazed moment and said Clary and Simon were sixteen. For the purposes of this story they're eighteen and so are Isabelle, Maia and Aline. Jace and Jordan are nineteen, while Magnus, Alec and Helen are twenty. This means that the Climon friendship has been going on for twelve years and Clary and Jace were about ten, eleven when the incident occurred. I hope I've cleared that up!**

* * *

After multiple pinches and slaps across the face, Clary reluctantly admitted defeat. She definitely wasn't in a nightmare; she _had_ been partnered up with Jace. Luke knew what had happened eight years ago, and he'd agreed to put her with that stuck-up brat over her best friend? It didn't make sense.

As soon as everyone had found out their forever partner, Clary had retired to her room with complaints of a migraine, but it was really to stop herself from throttling Jace or Luke. She was beyond fuming about the whole situation.

A soft tap on the door brought her back to reality. "Are you still playing the dying swan in there?"

_Oh great._ "Don't you have anything better to do rather than pestering me, Herondale? Maybe pick up a few chicks?"

"C'mon Shortcake, just open the door." Clary could literally feel him smirking on the other side. "You missed the briefing for tomorrow, so Luke asked my _wonderful_ self to explain what our duties include."

Clary sighed and sat on the end of her bed, not in the mood to fight. "Hurry up, then."

Jace swung the door open and leaned against the door frame, glancing at her expectantly. "Are you going to invite me in, then?"

"I did. Get your ears tested." Clary snapped.

"You told me to hurry up, _not _come in," he pointed out nonchalantly, narrowing his eyes at her. "You're oddly grumpy today. Period?"

Clary wanted to kill him, but she could feel a flush creeping onto her freckled face. "Just get in, close the door and take a seat."

Shockingly he obeyed her without a cocky remark, slumping down on the wooden chair next to the window where she tended to sit while drawing. The remnants of the sunset were flooding into her room anyway, slightly illuminating parts of Jace's angular face that was currently fully distorted by his trademark smirk. For the first time in eight years, Clary decided to put her anger at him aside and study him intently. He'd grown up so much since the incident; it agonized Clary to realise that if anything he was more attractive than before. Rather than having a child's body, he'd morphed into his fully grown state, which was muscular as a result of intense physical training but still very lean. His hair had grown to the point where the curled ends just brushed the tops of his shoulders, but it still remained a silky tangle of straw coloured curls that looked like gold in the light. His fair eyelashes had grown out a fair bit, casting shadows beneath. The only thing that remained of the boy she once knew were his eyes - they still remained their unique shade of gold. Looking at him now made it even harder to believe that he'd once befriended a dumpy girl with hair like Raggedy Ann and a face full of freckles. Nonetheless, his appearance was beautiful, but his soul was not.

"So in the morning we as a pair have training time. I think we should run a few fights just to test skill in case something happens, though it should be okay. After lunch we're heading to question someone who was attacked by The Circle for being caught eavesdropping to see if we can get a vague idea on what they're planning. Then we're wanted to do a quick patrol around that area for suspicious activity before getting takeout for everyone, then in the evenings as always it's free time unless there's a call." Jace explained the entire thing effortlessly which just made Clary more frustrated with him. "Thanks. Now leave."

He narrowed his eyes again, rising up from the chair suddenly. "Got enough tampons, Shortcake?" he queried.

"I'm not on, you stupid twit," Clary snarled, clenching her fists tightly to stop herself punching him. "You're an ass with an ego larger than the entire North American continent."

"Only that? I was expecting something _far_ larger," Jace remarked with a crooked grin. "But in all seriousness, are you okay? Have you taken anything for the migraine?"

First he came in insulting her, _now _he was concerned? Nuh-uh, Clary wasn't falling for that. "Just leave me be, Jace. I don't want to talk to you."

He sighed ruefully and headed to the door, turning as he went to close it behind him. "Meet me at nine in the training room. If you want to hang out downstairs we're playing a very intense game of MarioKart which I'm winning, obviously."

Once he left, Clary cried out in frustration and flopped back onto her bed, face first into her pillows. A sob racked her tiny body as she allowed everything to spill out. She was sick and tired of absolutely _everything_ in her life right now, and worst of all, she actually missed Jace. He'd always been nice to her before the incident, and if she was honest losing him scarred her emotionally. She wasn't the same; less open, more secretive.

An hour passed and she'd recovered, so she got changed into a baby pink camisole and white shorts before retreating under the covers with her sketchbook in hand. Turning on the bedside light, she flipped open the sketchbook to a drawing she'd started yesterday. Using a picture as reference, she was drawing the group picture they'd had after 'graduating' a few weeks ago. They'd all had dinner at a fancy restaurant with Luke who'd taken the picture for them just outside it after eating. Everyone had a cheesy grin painted on their face as they all stood in formal wear and anticipated when they'd get their partners. So many jokes had come out of that night as people recalled memories of training and made hilarious comments about some possible partner pairings.

From left to right the order in the picture was Alec, Jace, Isabelle, Clary, Simon, Aline, Maia, Jordan, Helen and Magnus. The boys had all dressed up in black and white suits as requested by Luke (though Magnus had insisted on having glitter in his hair still, he couldn't have glitter on his suit), while the girls got a choice on dresses. They'd all brought dresses and gotten ready together, though Isabelle had most of the say in what they'd wore. Helen had her pale white-gold hair up in an elegant bun and wore a short white dress with long sleeves, lace embroidered across the chest and white heels. She'd always been so pretty in Clary's eyes and had adopted a motherly role in the group, being the second oldest behind Magnus. Aline wore a dress somewhat similar to Helen's but it was longer and in peach, plus she wore matching plain flats rather than heels. Her short black hair had been curled. With Isabelle being Isabelle, she'd struggled to get past Luke's rule of 'no looking like a hooker', but she still looked stunning in a flowing sleeveless red cocktail dress that exposed her slender calves, insanely high black high heels that allowed her to tower nearly everyone and her ink black hair scraped back into a French braid with red flowers clipped in parts of the braid. Maia had worn a short sleeveless gold dress with a sequined bust line and sequined gold heels to match, not to mention the huge gold flower clipped onto the left side of her straightened golden-brown hair. Clary had reluctantly agreed to let Isabelle pick a dress for her and the girl had actually done okay, having picked out a tea length green vintage cocktail dress and plain silver heels. Her carrot coloured curls had been left to cascade down her back much to Isabelle's despair, but Clary had never been a fan of putting her hair up.

She was focused on drawing Alec's messy black hair - she'd drawn the basic outlines of everyone yesterday - when she decided to call it a night.

* * *

Clary had gotten dressed into a white camisole, black leggings, red converse and tied her hair up in a low messy bun in the morning, making her way to the training room at nine sharp. As much as she would have liked to been late to spite him, training was important to her and she wouldn't miss it, even if it was with Jace.

When she entered the room, Jace was already in there beating the absolute life out of a punching bag. Well, if they had lives, anyway.

"Right, I'm here," Clary announced nonchalantly, throwing her hands up. "What do you want to do?"

Jace froze abruptly, turning his head to smirk at Clary. "Hello to you too, Shortcake," he said, his gaze resting on her shoes. "Training is more effective with socks or barefoot. You should know that by now."

She _did_ know that, but in the rush of the moment she'd forgotten. Whoops.

Once she'd removed her shoes to remain in white socks, she stood on the safety mat and rose her clenched fists. "Fight me, then. I didn't get up to stand around watching you show off."

Jace turned fully from the punching bag and crossed the room in a white t-shirt, black shorts and no socks. On stepping onto the safety mat, he lifted his gold gaze to meet Clary's green eyes. "You can make the first move." he offered.

Clary shook her head adamantly. "The enemy won't give you the first move. They'll either lunge at you or circle around until they or you go for it."

"As you wish."

The two circled each other with observant eyes until Clary decided to just take the first move, landing a punch to his throat. He gagged for air for a moment, allowing her to knee him in the stomach, but he kicked the ankle she was still standing on so she toppled to the ground. He kicked her straight in the ribs several times until she rolled away from his beating, springing up to her feet and punching him in the face.

They continued their intense duel for probably five minutes more until Jace had knocked Clary to the floor for the sixth or seventh time, causing her to smack her head to the safety mat with a force so strong she could had sworn she could have broken her skull. It hurt to move it from where she was, so she had to surrender. "Stop, stop! I'm done!" she cried, breathing heavily and squeezing her eyes shut to stop her crying. She _refused_ to cry in front of the asshole who'd caused the pain.

Jace chuckled in mild amusement. "Not bad, Shortie. I think you might have got that if I didn't just knock you down."

"For the love of God, will you please stop calling me that-" Clary broke off as a surge of pain suddenly hit her, making her grit her teeth in agony. "Fuck, I can't get up."

She couldn't see, but she felt a large callused hand on her forehead. "You're burning up. Are you okay?"

"What do you _think_, dickhead?" Clary snapped. "I hit my head when you knocked me down!"

The hand on her head tensed. "Can you open your eyes?"

She suddenly felt nauseous and dizzy. "I feel faint..."

"Right, I'm going to find someone, but I think Luke's out." Jace removed his hand and stood up, but Clary had this strange feeling wash over her of not wanting to be alone. "No. Stay, please."

She felt him sit beside her and heave a sigh, pulling her over to him with a grunt so her throbbing head rested in his lap. The pain was excruciating; she lost the battle to kill her tears and her eyes flung open.

Jace wiped away some tears from her cheeks with his thumb like he would have done when they were still friends. "Hey, shhhh. I'm sorry." he murmured softly.

That was the last thing she heard before slipping into a sea of darkness.

* * *

**Dun dun dunnnn... you'll learn more about the plot next chapter, promise!**

**Just to give you an idea, there are pictures of the dresses the girls wore to the graduation meal on my profile.**


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